The present invention relates to a heat resisting robot hand apparatus for placing into and removing from a chamber a material to be heated, such as a semiconductor wafer, the chamber having a high temperature and a reduced pressure for manufacturing semiconductor devices and the like.
FIG. 8 shows, in cross section, a conventional robot hand for placing into and removing from a chamber a material such as a semiconductor wafer to be heated in a chamber which contains therein a heater for heating the material to a high temperature so as to dry it. In this figure, a box-shaped chamber 1 contains therein a heat stage 5 suspended from the ceiling of the chamber I for-heating a semiconductor wafer 3, and a hanger 7 comprising a plurality of L-shaped rods for vertically supporting a semiconductor wafer 3. The chamber 1 is provided at one side with a gate 9 through which the semiconductor wafer 3 can be inserted into the chamber 1 under the action of the robot hand, which is generally denoted at reference numeral 11. The robot hand 11 comprises a hand section 13 formed of a generally quadrilateral flat plate for supporting thereon the semiconductor wafer 3, and an arm section 17 fixedly connected to one end of the hand section 13 via screws 15. Though not illustrated, a pressure reducing means such as a vacuum pump is connected to the chamber 1 for reducing the pressure in the chamber 1 to an appropriate level.
The operation of the robot hand 11 illustrated in FIG. 8 will now be explained below. The arm section 17 is first caused by an unillustrated arm driving means to contract and pull the hand section 13 out of the chamber 1. In this state, the semiconductor wafer 3 is then placed on the hand section 13, and the arm section 17 is caused by the unillustrated arm driving means to extend or move into the chamber 1 so as to insert the semiconductor wafer 3 into the chamber 1. Before the hand section 13 has been inserted into the chamber 1, the top end of the hanger 7 is caused by an unillustrated drive mechanism to descend to a location lower than the hand section 13. When the hand section 13 and the wafer 3 has been inserted into a predetermined position of the chamber 1, the hanger 7 is raised to such an extent that the top surface of the wafer 3 abuts against the bottom surface of the heat stage 5 while claws 7a at the bottom end of the hanger 7 are holding the wafer 3. Subsequently, the heat stage 5 is powered by an unillustrated power source to heat and dry the wafer 3. After the wafer 3 has been sufficiently dried, the hanger 7 is lowered so that the wafer 3 is transferred to the hand section 13 which has been waiting at a location below the heat stage 5. At this time, the hanger 7 is descended to a location slightly lower than the hand section 13, and thus, the wafer 3 is totally released from the hanger 7 and supported by the hand section 13 alone. The arm section 17 is moved to the outside of the chamber 1, and accordingly, the hand section 13 together with the wafer 3 is pulled out of the chamber 1 through the gate 9. Subsequently, the thus dried wafer 3 is removed from the hand section 13 and transferred to a next stage for the following processing. A new undried wafer 3 is placed on the hand section 13, and a series of operations described above are repeated.
However, the foregoing conventional robot hand presents the following problems. While the wafer 3 is supported by the hanger 7 and it is heated and dried by the heat stage 5, the robot hand 11 is vulnerable to radiant heat from the heat stage 5 and the wafer 3. Also, while the heated wafer 3 is on the hand section 13, the heat emitted from the wafer 3 is directly transferred to the hand section 13 through the area of contact between the wafer 3 and the hand section 13. Thus, the robot hand 11 is exposed to thermal deterioration and distortion during a long period of use, thereby changing the position of transferring the wafer 3 between the hand section 13 and the hanger 7, and thus failing to correctly transfer the wafer 3 therebetween. A crack may also occur in the robot hand 11, in particular, in the hand section 13 due to the thermal stress. Further, the heat emitted from the hand section 13 is transferred to the arm section 17 so that a drive controlling section (not shown) arranged on the arm section 17 is thermally deteriorated.